GLProgramsTest can now randomly create a tree of GrFragmentProcessors instead of a linear pipeline

src/gpu/effects/GrXfermodeFragmentProcessor.cpp

 /*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "effects/GrXfermodeFragmentProcessor.h"
 
 #include "GrFragmentProcessor.h"
@@ skipping 129 matching lines @@
 }
 
 
 const GrFragmentProcessor* GrXfermodeFragmentProcessor::CreateFromTwoProcessors(
          const GrFragmentProcessor* src, const GrFragmentProcessor* dst, SkXfermode::Mode mode) {
     if (SkXfermode::kLastCoeffMode < mode) {
         return nullptr;
     }
     switch (mode) {
         case SkXfermode::kClear_Mode:
-            SkDebugf("CreateFromTwoProcessors() should not be used with kClear_Mode. "
-                     "Use GrConstColorProcessor.\n");
             return GrConstColorProcessor::Create(GrColor_TRANS_BLACK,
                                                  GrConstColorProcessor::kIgnore_InputMode);
             break;
         case SkXfermode::kSrc_Mode:
-            SkDebugf("CreateFromTwoProcessors() should not be used with kSrc_Mode. "
-                     "Use the src processor directly.\n");
             return SkRef(src);
             break;
         case SkXfermode::kDst_Mode:
-            SkDebugf("CreateFromTwoProcessors() should not be used with kDst_Mode. "
-                     "Use the dst processor directly.\n");
             return SkRef(dst);
             break;
         default:
             return new GrComposeTwoFragmentProcessor(src, dst, mode);
     }
 }